The present invention relates to the field of automotive hoses. More particularly, the present invention relates to the field of hoses used in the automotive industry that typically include elastomer materials.
There is a growing demand for lighter automotive hoses that are used for transporting such compounds as fuels, refrigerant, and other volatile gases and fluids. The hoses must have a low permeability to provide a barrier for gases both outside and inside the hose. The hoses must also be flexible enough to absorb the vibration of the automotive components to which they are connected. Further, the hoses must be able to withstand the high temperatures that exist in the automobile engine environment, as well as the corrosive compounds that tend to accumulate in that environment.
In view of these considerations many automotive hoses employ a polyacrylate material, taking advantage of its combined softness and strength, or chlorinated polyethylene (CPE) material. However, there is a need for automotive hoses made from materials having greater dimensional stability or xe2x80x9cgreen strength.xe2x80x9d There is also a need for automotive hoses that have improved processability. Specifically, it is desirable to eliminate the post-cure step normally associated with hose manufacturing. The hose should have better aging properties than hoses that incorporate CPE material, and at least maintain the aging properties of hoses incorporating polyacrylate material.
The above-described needs and others are met by the present invention, which may be embodied and described as a multilayer automotive hose, which includes an innermost layer of elastomer material, and a separate outermost layer of elastomer material. Each of the innermost layer and outermost layer includes between about 40% and about 80% vinylacetate by weight in a copolymer. The concentration of vinylacetate is most preferably between about 60% and about 70% by weight. The elastomer layers are formed by an extrusion process. The vinylacetate in the innermost and outermost layers is copolymerized with polyethylene. Each of the elastomer layers has a fully saturated backbone. As a result, each of the innermost and outermost layers is a non-thermoplastic elastomer.
The automotive hose further includes a middle layer made up of reinforcement fibers, disposed between the innermost and outermost layers. The middle layer is preferably disposed directly between the innermost layer and the outermost layer.
Each of the innermost layer and outermost layers is preferably a nonhalogenated elastomer. LEVAPREN(trademark) EVM elastomer materials made by Bayer Corp. are used in a most preferred embodiment of the invention, and are made from ethylene-vinyl actetate copolymer rubber.
Additional advantages and novel features of the invention will be set forth in the description which follows or may be learned by those skilled in the art through reading these materials or practicing the invention. The objects and advantages of the invention may be achieved through the means recited in the attached claims.